Coordination polymerization catalyst

ABSTRACT

A COORDINATION CATALYST FOR POLYMERIZING OLEFINS, DIOLEFINS AND ALKYLENE OXIDES, CONSISTING ESSENTIALLY OF   (A) AN IRON COMPLEX COMPRISING A LIGAND CONTAINING OXYGEN DONOR ATOMS AND SELECTED FROM THE GROUP CONSISTING OF IRON ACETYLACETONATE, IRON OCTOATE AND IRON NAPHTHENATE; (B) A TRIALKYL ALUMINUM COMPOUND; AND (C) A BIDENATE LIGAND CAPABLE OF BOTH PI AND SIGMA BONDING TO FORM A FIVE- OR SIX-MEMBERED CHELATE RING, SAID LIGAND BEING CHARACTERIZED BY THE STRUCTURAL FORMULA   ((R)Y-PYRID-2-YL)-(C(-R)2)X-C(-R)M=N-(Q)M   WHEREIN M IS A NUMBER FROM 0 TO 1, X IS A NUMBER FROM 0 TO 1, Y IS A NUMBER FROM 0 TO ABOUT 4, R IS A RADICAL SELECTED FROM THE GROUP CONSISTING OF HYDROGEN, ALKYL, ARYL, HALOGEN, HYDROXYL, AND ACETOXY, AND Q IS A RADICAL SELECTED FROM THE GROUP CONSISTING OF HYDROGEN, ALKYL, HALOGEN, HYDROXYL AND ACETOXY, THE MAJOR PORTION OF SAID SIGMA BONDING BEING ATTRIBUTABLE TO THE RING NITROGEN, WHEREIN THE MOLAR RATIO OF TRIALKYL ALUMINUM COMPOUND TO IRON COMPLEX IS FROM ABOUT 1/1 TO 4/1 AND THE MOLAR RATIO OF BIDENTATE LIGAND TO THE IRON COMPLEX IS FROM ABOUT 0.1/1 TO ABOUT 2.5/1.

United States Patent 3,677,968 COORDINATION POLYMERIZATION CATALYST JohnE. Bozik, Pittsburgh, Harold E. Swift, Gibsonia, and Ching-Yong Wu,Pittsburgh, Pa., assignors to Ameripol, Inc., Cleveland, Ohio NoDrawing. Original application Mar. 10, 1969, Ser. No. 812,536, nowPatent No. 3,565,875, dated Feb. 23, 1971. Divided and this applicationJuly 9, 1970, Ser.

Int. Cl. C08d 3/06, 3/08 US. Cl. 252431 N 13 Claims ABSTRACT OF THEDISCLOSURE A coordination catalyst for polymerizing olefins, diolefinsand alkylene oxides, consisting essentially of (a) an iron complexcomprising a ligand containing oxygen donor atoms and selected from thegroup consisting of iron acetylacetonate, iron octoate and ironnaphthenate;

(b) a trialkyl aluminum compound; and

(c) a bidentate ligand capable of both pi and sigma bonding to form afiveor six-membered chelate ring, said ligand being characterized by thestructural formula E sa...

LBJ, wherein m is a number from to 1, x is a number from 0 to 1, y is anumber from 0 to about 4, R is a radical selected from the groupconsisting of hydrogen, alkyl, aryl, halogen, hydroxyl, and acetoxy, andQ is a radical selected from the group consisting of hydrogen, alkyl,halogen, hydroxyl and acetoxy, the major portion of said sigma bondingbeing attributable to the ring nitrogen, wherein the molar ratio oftrialkyl aluminum compound to iron complex is from about 1/1 to 4/1 andthe molar ratio of bidentate ligand to the iron complex is from about0.1/1 to about 2.5/1.

This is a division of copending application Ser. No. 812,536 filed Mar.10, 1969, now US. Pat. No. 3,565,875.

BACKGROUND OF THE INVENTION This invention relates to the polymerizationof certain olefins, diolefins and alkylene oxides. More specifically,this invention relates to the rapid, relatively low temperaturepolymerization of a wide variety of organic monomers in high yieldsemploying a highly specific three component catalyst system.

Many catalyst systems heretofore employed have been limited in theirapplicability due to their inability to catalyze polymerization activityin a variety of diilerent monomers. Instead, most catalyst systems areemployed to aid in the polymerization of a highly specific and narrowclass of monomers. The restricted applicability of such catalyst systemsseverely limits the flexibility and range of commercial plantoperations.

Specifically, coordination catalysts are generally limited in theirability to polymerize either polar or non-polar monomers. Few, if any,coordination catalysts are known to polymerize both polar and non-polarmonomers. In addition, although coordination catalysts generally consistof at least one metallic component, few, if any, of such catalysts haveheretofore been employed to obtain high molecular weight polymeremploying an iron compound as -a metallic compound. Iron compounds,though stable, inexpensive and readily available have basically beenrelegated as catalyst components to oligomerization.

Patented July 18, 1972 fice SUMMARY OF THE INVENTION These, as well asother objects, are accomplished in accordance mm the present inventionwhich provides a process comprising polymerizing monomers selected fromthe group consisting of:

(a) olefins having the formula:

H2C::CR1R2 wherein R can be a halogen or an alkyl group contalning from1 to 4 carbon atoms and R can be a halogen or a cyano radical; (b)diolefins; and (c) alkylene oxides having the formula:

RCHOH2 \O wherein R is hydrogen or an alkyl or aryl group contaming from1 to about 6 carbon atoms;

in contact with a catalytically efi'ective amount of a catalyst systemcomprising:

(i) an iron complex comprising a ligand containing oxygen donor atoms;

(ii) a trialkyl aluminum compound; and

(iii) a bidentate ligand capable of both pi and sigma bonding to form afive or six-membered chelate ring, characterized by the structuralformula:

wherein m is a number from O to l, x is a number from 0 to 1, y is anumber from 0 to 4, R is a radical selected from the group consisting ofhydrogen, alkyl, aryl, halogen, hydroxyl and acetoxy, and Q is a radicalselected from the group consisting of hydrogen, alkyl, halogen, hydroxyland acetoxy, the major portion of said sigma bonding being attributableto the ring nitrogen DESCRIPTION OF' THE INVENTION The catalyst systemof the present invention is useful in polymerizing a wide variety ofmonomers both polar and nonpolar. For example, monomers which arepolymerizable in accordance with the present invention are exemplifiedby:

(a) olefins having the formula:

H C=CR R wherein R can be a halogen such as chlorine, bromine, iodineand fluorine or an alkyl group containing from 1 to about 4 carbon atomssuch as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl,tert.-butyl and the like, and R can similarly be a halogen or a cyanoradical. llllustrative of such olefins are vinylidene chlorine,methacrylonitrile, vinylidene fluoride and the like; (b) diolefinsespecially the aliphatic acyclic conjugated diolefins containing fromabout 4 to about 12 carbon atoms such as butadiene, isoprene,piperylene, 2,3-di methyl-butadiene, 1,3-pentadiene, chloroprene and thelike; and (c) alkylene oxides having the formula:

RCE-CH1 wherein R is an alkyl or aryl group containing from 1 to about 6carbon atoms such as methyl, ethyl, propyl, butyl, phenyl and the like,or hydrogen. For example, ethylene oxide, propylene oxide, styrene oxideand the like have been found suitable.

In addition, the catalyst system of the present invention has been founduseful in preparing copolymers of the various monomers set forthhereinabove. Surprisingly, although vinyl aromatics such as styrene werefound to be inactive with the catalyst system of the present invention,they were found to copolymerize with the monomers set forth above.

Polymerization is obtained in accordance with the present invention bycontacting at least one of the monomers described hereinabove with thethree component catalyst system of the present invention in an inertdiluent, if desired (although the use of such diluent is not considerednecessary) at relatively low temperature, generally ranging from about50 C. to about 150 C. The polymerization proceeds rapidly resulting inhigh yields of polymer.

The catalyst system is a three component system comprising:

(i) an iron complex comprising a ligand containing oxygen donor atomssuch as, for example, iron (III) acetylacetonate, iron (III)naphthenate, iron octoate and the like;

(ii) a trialkyl aluminum preferably wherein the alkyl groups eachcontain from 1 to about 8 carbon atoms, for example, methyl, ethyl,n-propyl, isopropyl, n-butyl, sec-butyl, iso-butyl, hexyl, octyl and thelike. Illustrative of such compounds are triethyl aluminum,tri-isopropyl aluminum, tri-isobutyl aluminum, tri-n-butyl aluminum,tri-octyl aluminum and the like; and

(iii) a bidentate ligand capable of both pi and sigma bonding to form afive or six-membered chelate ring, said ligand being characterized bythe structural formula:

\ R (R) fg-tint...

wherein R can be a radical such as hydrogen, alkyl, preferably alkylscontaining from 1 to about 8 carbon atoms such as methyl, ethyl,iso-propyl, tert.-butyl, hexyl, octyl and the like; aryl such as phenyl,benzyl and the like; halogen such as chlorine, bromine, iodine andfluorine; hydroxyl and acetoxy; Q can be a radical such as hydrogen,alkyl, preferably alkyls containing from 1 to about 8 carbon atoms suchas methyl, ethyl, iso-propyl, tert.-butyl, hexyl, octyl and the like,halogen such as chlorine, bromine, iodine and fluorine; m is a numberfrom 0 to 1, x is a number from 0 to 1 and y is a number from '0 to 4.

Illustrative of the various ligands encompassed herein are the followingexamples which are not to be construed as imposing any limitation on thescope of the structural formula set forth hereinabove:

(Rly

, it o wherein R, Q and Y are as defined above. Examples of suchbidentate ligands are 2-cyanopyridine, phenyl-2-pyridylacetonitrile,2-cyano-6-methylpyridine, Z-pyridinealdoxime and the like.

The three component catalyst system of the present invention is highlyspecific in that all three components must be present for the catalystsystem to be active. In addition, it has been found that therequirements for each component are quite rigid. Many closely analogousmaterials for each catalyst component have proven inoperable or werefound to result in extremely low yields of polymer or the formation ofonly dimers and trimers. For example, although iron acetylacetonate is asuitable iron complex, the following metal acetylacetonates M(AA) haveproven inoperable: Ni(AA) Co(AA)2 CO(ALA)3, )3, )3, )z, )4 )3 andZI1(AA)2.

In addition, although trialkyl aluminum compounds have proven suitable,other organometallic compounds have been found inoperable such as, forexample, dialkyl aluminum halides, alkyl aluminum dihalides, phenylmagnesium chloride, di-sec-butyl magnesium and triethyl boron.

Still further, although many pyridine compounds and nitriles have provento be suitable bidentate ligands, other closely analogous materials andeven isomers have proven inoperable. For example although2-cyanopyridine is operable, 3-cyanoand 4-cyanopyridine have been foundinoperable. Similarly, 2-aminomethyl pyridine, di-Z-pyridyl ketone,2-cyanoaniline, 2-acetyl pyridine, acetonitrile and 2-vinyl pyridinehave been found inoperable.

It has been found in the present invention that in order to obtain anactive polymerization catalyst, the ligand must be capable ofcoordinating with reduced iron in two positions, or function as abidentate ligand. With 3 and 4-cyanopyridine, chelate rings cannot formand use of these compounds results in inactive systems.

(EEN

\N \N \N l C I l Fe4-N 4-cyanopyridine 2-cyanopyridine-lronZ-cyanopyridlne inactive complex-active inactive Although not wishing tobe bound by any theory or mechanism, the relatively low activity of theFe (AA) TEA-2-cyano-6-methylpyridine system strongly suggests a sterichindrance effect. The steric hindrance could be a physical blocking orinterference of the incoming monomer.

tuft

2-cyano-6-methylpyridlne-iron complex low activity meter. The necessityof having the nitrogen donor atom in the aromatic ring is demonstratedby the inactivity of 2-cyano-aniline.

-CH -C H OH=CH C N I NHa l 2-aminon1ethyl pyridine vinylpyridine2-cyano-ani1ine The specificity of the ligand makes this catalyst systemanalogous to enzymatic action. The ligand must have side chainunsaturation to participate in d1r-p1r bonding with the iron orbitalsand stabilize the reduced valence state of iron. But yet the ligand hasto have a donor atom in the side chain and in the aromatic ring toparticipate in mainly sigma bonding. Thus, it appears to be necessary tohave a critical balance of a' and 11' bonding in conjunction withstringent factors to have an active catalyst system.

Thus, it can readily be seen that the three component coordinationcatalyst of the present invention is highly specific with regard to themake-up of the three components.

The molar ratio of the trialkyl aluminum compound to the iron complexAl/Fe can be varied from about 1/1 to about 4/1; however, higher yieldsof polymer can be obtained at Al/Fe ratios of from about 2.5 to about3.5 with optimum yields being secured at ratios of about 3. The molarratio of the bidentate ligand to the iron complex, ligand/Fe, can bevaried from about 0.1/1 to about 2.5/1 with best results being obtainedwithin the range of about 0.5 to about 1.5. Small amounts of thecatalyst system have been shown to be catalytically effective in thepolymerization of the wide variety of monomers set forth hereinabove.For example, the molar ratio of monomer to iron complex, monomer/Fe, canvary from about 100/1 to about 400/ 1 without adverse eifect on the rateof reaction or the efliciency of polymerization.

The polymerization reaction proceeds readily under normal conditions oftemperature and pressure. The temperature can vary widely from about 50C. to about 150 C.; preferably and most conveniently, however, thereaction proceeds at or about room temperature (25" C.). Althoughautogenous pressure developed during polymerization is generallysufficient, any pressure can be employed such as subatmospheric,atmospheric or superatmospheric. It is considered preferable that thereaction proceed under anhydrous conditions in an inert atmosphere suchas under a blanket of nitrogen, argon, neon, and the like.

It is not considered necessary that an inert organic solvent or diluentbe employed in the polymerization process; however, if desired, it hasbeen found that the selection of the solvent is not critical andessentially any hydrocarbon solvent can be employed. The solvents can bearomatic, aliphatic or even halogenated hydrocarbons without adverseeffect on the process. For example, solvents such as benzene, toluene,o-dichlorobenzene, n-hexane, heptane, 1,2-dichloroethane and the likehave been found suitable. Preferably, aromatic hydrocarbon solvents areemployed, such as benzene, toluene and the like, since these solventshave been found to provide a greater rate of polymerization.

Typically, the polymerization process proceeds in the following manner:to a dry 200 milliliter polymerization vessel is charged 0.1 millimoleof iron acetylacetonate, 0.1 millimole of phenyl-2-pyridylacetonitrile,40 milliliters of benzene, 20 milliliters millimoles) of isoprene and0.3 millimoles of triethyl aluminum in that order. The particular orderof addition is not considered critical and can be altered, if desired.All reactants are kept under a dry nitrogen atmosphere at all times. Thepolymerization vessel is then sealed and the reaction is allowed toproceed with agitation at room temperature until completion. Generally,high conversions of about 75 percent are easily obtained within arelatively short period of time. The resulting polyisoprene cement isthen poured into alcohol such as methanol, ethanol, or the like tocoagulate the polymer. The resulting polymer is then dried andrecovered.

The following examples are cited to further illustrate variousembodiments of the present invention and should not be construed asimposing any restriction or limitation upon the scope or spirit of thepresent invention.

Example 1 A 2000 milliliter resin kettle equipped with a stirrer,nitrogen inlet and outlet and a 250 milliliter addition flask was usedas the reaction vessel. The kettle was thoroughly dried at C. andallowed to cool to room temperature in a stream of dry nitrogen. Thereactants were prepared in a nitrogen atmosphere in a glove box. To theresin kettle was added a solution of 4 millimoles of ironacetylacetonate, 4 millimoles of 2-cyanopyridine, milliliters of benzeneand 80 milliliters of isoprene. Thereafter, a solution of 12 millimolesof triethyl aluminum in 30 milliliters of benzene was added. A stream ofnitrogen was kept flowing through the' kettle at all times. When thereaction mixture became highly viscous, an additional 250 milliliters ofbenzene was added from the addition flask. The reaction was allowed toproceed for about 2 hours. The resulting polymer was then diluted withenough benzene to reduce the viscosity to a level where it would flowfreely (about 500-1000 milliliters of benzene is generally suflicientfor such purpose). Antioxidant was added to the solution. The dilutesolution was then run into a methanol bath to coagulate the polymer. Therecovered polymer Was then dried in a vacuum oven. Infrared analysisestablished the polymer as being polyisoprene exhibiting the followingmicrostructure: 50% cis-l,4, 3% trans-1,4, 2% 1,2 and 45% 3,4.

Example 2 Employing substantially the same procedure described inExample 1, several ligands were evaluated in lieu of 2- cyanopyridine inthe three component catalyst system for the polymerization of isoprene.Table 1 summarizes the results obtained:

TABLE I Effect of ligand on yield of polyisoprene Ligand: Percent yieldof polymer Z-cyanopyridine 60 7 Example 3 Employing substantially thesame procedure described in Example 1, several iron complexes wereevaluated in lieu of the iron acetyl acetonate in the three componentcatalyst system for the polymerization of isoprene. Table II summarizesthe results obtained:

TABLE II Effect of iron complex on yield of polyisoprene Iron complex:Percent yield of polymer Iron acetylacetonate 60 Iron naphthanate 60Iron octoate 50 Ferric chloride 0.5

Iron pentacarbonyl O Diiron monacarbonyl Example 4 Employingsubstantially the same procedure described in Example 1, severaltransition metal acetylacetonates were evaluated in lieu of the ironacetylacetonate in the three component catalyst for the polymerizationof isoprene. Table III summarizes the results obtained:

TABLE III Eifect of transition metal acetylacetonates on yield ofpolyisoprene Metal acetylacetonate (M(AA), Percent yield of polymerFe(AA) 6 Ni(AA) Co(AA) Co(AA) )s X(AA) Mn(AA) Zr(AA) Ce(AA) Cd(AA) )2OOOQOOOOOQOO Example 5 Employing substantially the same proceduredescribed in Example 1, several organometallic reducing agents wereevaluated in lieu of the triethyl aluminum in three component catalystfor the polymerization of isoprene. Table IV summarizes the resultsobtained:

Employing substantially the same procedure described in Example 1, awide variety of olefinic, diolefinic and alkylene oxide monomers werepolymerized. Table V summarizes the results obtained:

Example 7 Employing substantially the same procedure as set forth inExample 1, butadiene was polymerized at 0 C. in hexane solvent; aconversion of about 75 percent was achieved in about 2 hours. Infraredanalysis indicated a polybutadiene exhibiting the followingmicrostructure: 14% trans-1,4; 33% cis-1,4 and 53% 1,2.

Example 8 Employing substantially the same procedure described inExample 1, a mixture of isoprene and styrene (50 mole percent styrene)was charged to the polymerization vessel. The recovered copolymer wasfound to contain 18.6 mole percent styrene.

The polymers obtained in accordance with the present invention rangefrom elastomeric polymers to plastics and resins. These polymers areuseful in adhesives, belts, films, fibers, tire manufacture, electricalinsulation and other similar uses.

What is claimed is:

1. Catalyst system consisting essentially of (a) an iron complexcomprising a ligand containing oxygen donor atoms and selected from thegroup consisting of iron acetylacetonate, iron ocoate and ironnaphthenate;

(b) a trialkyl aluminum compound; and

(c) a bidentate ligand capable of both pi and sigma bonding to form afiveor six-membered chelate ring, said ligand being characterized by thestructural formula wherein m is a number from 0 to 1, x is a number from0 to 1, y is a number from 0 to about 4, R is a radical selected fromthe group consisting of hydrogen, alkyl, aryl, halogen, hydroxyl, andacetoxy, and Q is a radical selected fromt he group consisting ofhydrogen, alkyl, halogen, hydroxyl, and acetoxy, the major portion ofsaid sigma bonding being attributable to the ring nitrogen, wherein themolar ratio of trialkyl aluminum compound to iron complex is from about1/1 to 4/1 and the molar ratio of bidentate ligand tot he iron complexis from about 0.1/1 to about 2.5/1.

2. Catalyst system as defined in claim 1 wherein the trialkyl aluminumis comprised of alkyl groups containing from 1 to about 8 carbon atoms.

3. Catalyst system as defined in claim 1 wherein the bidentate ligand ischaracterized by the structural formula:

GEN

5. Catalyst system as defined in claim 1 wherein the bidentate ligand ischaracterized by the structural formula:

wherein R is a radical selected from the group consisting of hydrogen,alkyl, aryl, halogen, hydroxyl and acetoxy, Q is a radical selected fromthe group consisting of hy drogen, alkyl, halogen, hydroxyl and acetoxy,and y is a number from to about 4.

6. Catalyst system as defined in claim 5 wherein the bidentate ligand isZ-pyridinealdoxime.

7. Catalyst system as defined in claim 1 wherein the bidentate ligand ischaracterized by the structural formula:

wherein R is a radical selected from the group consisting of hydrogen,alkyl, aryl, halogen, hydroxyl and acetoxy, and y is a number from 0 toabout 4.

8. Catalyst system as defined in claim 7 wherein the bidentate ligand isphenyl-2-pyridylacetonitrile.

10 9. Catalyst system as defined in claim 1 wherein the bidentate ligandis characterized by the structural formula:

wherein R is a radical selected from the group consisting of hydrogen,alkyl, aryl, halogen, hydroxyl and acetoxy, Q is a radical selected fromthe group consisting of hydrogen, alkyl, halogen, hydroxyl and acetoxy,y is a number from O to about 4.

10. Catalyst system as defined in claim 1 wherein the iron complex isiron acetylacetonate.

11. Catalyst system as defined in claim 1 wherein the iron complex isiron naphthenate.

12. Catalyst system of claim 1 consisting essentially of (i) ironacetylacetonate, (ii) triethyl aluminum, and (iii) 2-cyanopyridine.

13. Catalyst system of claim 1 consisting essentially of (i) ironacetylacetonate, (ii) triethyl aluminum, and (iii)phenyl-2-pyridylacetonitrile.

References Cited UNITED STATES PATENTS 3,441,627 4/1969 Schneider252431NUX PATRICK P. GA-RVIN, Primary Examiner US. Cl. X.R. 252-431 C

